Seatbelt devices for vehicles are known which include a pretensioner for retracting a webbing to properly restrain a passenger upon collision or emergency braking. According to the seatbelt devices, when a collision or an emergency braking is detected by an acceleration sensor, a gas generator is ignited to generate gas based on a detection signal, and the webbing is retracted by a pressure of the generated gas. By retracting the webbing in this manner, the passenger can be properly restrained.
In the seatbelt devices including the pretensioner, however, since the gas generator is ignited to generate gas for retracting the webbing by the pressure of the generated gas, the pressure of the gas becomes high. Therefore, the hot gas is likely to leak outside a case of the pretensioner, and further, the leaked hot gas is likely to diffuse.
As a countermeasure thereto, a pretensioner is disclosed, for example, in Patent Document 1, which includes a heat absorbing member formed of high thermal conductivity material and provided in a gas supply space where gas is supplied. With this configuration, thermal energy of the hot gas is absorbed by the heat absorbing member, and the temperature of the gas is thereby lowered, so that an influence of the leaked hot gas can be minimized.
However, in the pretensioner of Patent Document 1, since it is necessary to provide the heat absorbing member in the gas supply space, a space for the heat absorbing member must be secured in the gas supply space of the pretensioner. Further, the provision of the heat absorbing member in the pretensioner undesirably increases the number of necessary components and complicates the configuration of the pretensioner. Thus, it is difficult to minimize the diffusion of the hot gas generated in the pretensioner with ease and simple configuration.